Electrical fuse



Oct. 27, 1925- H. DAVIES ELECTRICAL FUSE Filed Oct. 21, 1919 HGZ INVENTOR: fla/m/m MIA 5 Patented Oct. 27, 1925.

UNITED vS T HOWARD DAVIES, OF PHILADELPHIA, PENNSYLVA-N IA.

ELECTRICAL Application filed October 21, 1919.

To all whom it may concern.

Be it known that I, HOWARD DAVIES, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented a certain new and useful Improvement in Electrical Fuses, whereof the following is a specification, reference being had to the accompanying drawing.

My invention relates to fuses of the class including a tubular casing of insulating material having metallicterminals at its opposite ends adapted to detachably secure a strip of fusible metal; said "terminals also having means to electrically connect said fuse strip with conductors leading to and from said casing.

As hereinafter described,-my invention includes a specific construction and arrangement of said terminals, comprising wedge abutinents which are respectively fixed in said casing at opposite ends thereof, and wedges which are movable in said casing, in oppositionto the respective abutment-s, to detachab-l'y secure the opposite ends of a fuse strip between them.

Moreover, my invention includes the various novel features'of construction and arrangement hereinafter more definitely speci- In the drawing; Fig. *I is a side elevation of a fuse embodying my invention.

Fig. II is a longitudinal-sectional view, of said fuse, taken on the line II, II .in Fig. I.

Fig. III is a lower'e'nd view of said fuse as shown in Fig. I.

Fig. IV is a transverse sectional view of said fuse, taken on the line IV, IV in FigII.

Fig. V is a transverse sectional view of said fuse, taken on-theline V, V in Fig. II.

Fig. VI is a face view of the cap washer shown in Fig. III, but detached fromthe fuse structure.

In said figures; the cylindrical tubular casing l is composed of insulating material, preferably vulcanized fiber, andhas the metallic screw nipples 2 threaded therein at its casing 1, so as to afford respective wedge abutments, in opposition to the parallel plane inclined facesv '8 of the respective complementarysemicylindrical wedges 9. Said Serial No. 332,213.

wedgesi) are niovable axially in said casing 1,-to clamp the respective ends of the fuse strip 10 between said wedges '9 and said wedge abutments As indicated in dotted lines in Fig. I, said fuse strip 10 is much wider at its ends which areengaged with the wedge elements aforesaid than at its intermediate portion; the latter being of a cross sectional area which is precisely predetermined in accordance with the rated capacity of the fuse. Said wedges 9 may be pressed into the position shown in Fig. II, by the fingers of the operator, the inclination of their plane faces being such as to afford adequate clamping action throughout the entire surfaces of said fuse strip 10 which are engaged by the respective terminals.

However, I find it convenient to provide each of said wedges with external grooves 11 which are preferably helically inclined, as indicated in dotted lines in Fig. I, to facilitate their-progressive engagement bythe tip of a screwdriver, or any other similar impleinentiby which the operator may find it convenient to withdraw said wedges from their clamped position shown. To prevent accidental displacement of said wedges, I provide the screw caps 12 which are respectively engaged with said nipples 2 and which contain the cap washers 13 which bear upon the outer ends of said wedges 9. Each of said washers .13 has a diametrical slot 14, best shown in Fig. VI, through which I prefer to extend the ends of the fuse strip so that the-latter may be marked, as indicated in III, to show the rated capacity of the fuse, for instance, as shown in said figure, 200 amps. 250 volts.

Therefore, it may be observed that, said nipples 2 comprise not only means arranged to engage sai-d'termi'nal members in the casing but-also means engaging said screw caps on said casing and preventing retraction of said wedges from clamped position.

I am aware that it is the usual practice to mark the casings of fuses of'this general class so as to indicate the caoacity of the fuse strips for which they are designed to be used. However, I find that, very often, and particularly in the case of renewal of fuse strips, fuse strips of less capacity are inserted in-the casings thus marked; with the result that the subsequent user thereof misled bv the marking upon the exterior of the casing as to what is the actual capacity above described, whereby the actual capac-" ity of the fuse strip itself is manifested upon of the structure as a fuse. Therefore, the provision of means in my improved fuse the exterior of the casing, is of great practical advantage.

In the form of my invention chosen for illustration; the terminals 5 are provided with respective electrical conducting elements 16, in integral relation therewith, which serve as blades for detachable electrical connection between opposite spring plates, of any suitable construction, which are indicated at 17 in Fig. 11. I am aware that it is not new to. provide a fuse of the general class of my invention with terminal blades, but, as ordinarily constructed, they are movablewith respect to the terminals and, therefore, get out of alinenient and are otherwise troublesome, because they are free to rotate, whereas, in accordance with my improved construction above described, the blades 16 are continuously maintained in alinement with each other y the same screws 3 which retain the terminal members 5 in'stationary relation with said casing 1.

As best shown in Fig. V1, the diametrical slot in the cap washer 13 is so shaped as to permit the extension of the blade 16 th rethrough, as in Fig. III, and said blades 16, being stationary in said casing l, as above described, thus preventthe rotation of said washers 13 when said caps 12 are rotated to apply and remove themwith respect to said nipples 2. However, it is to be understood that my invention is not limited to the provision of such conducting elements as the blades 16 upon the terminals 5. The blades 16 maybe omitted and any other suitable conductors be extended through the open ings in the cap washers 13, in electrical connection with said terminals 5. For instance, ordinary cylindrical wires may be extended into said caps 12 through the respective openings 14 and be clamped by rotation of said caps with the ends of the wires between the cap washers and the adjacent ends of the wedges 9.

I also find it convenient to provide said casing 1, with a removablelining 18, of insulating material, for instance, asbestos sheeting. V

Therefore, 1 do not desire to limit myself to the precise details of construction and arrangement herein set forth, as it is obvious that various modifications may be made therein, without departing from the esse'ir tial features of my invention as defined in the appended claims.

I claim: 1

1. In an electrical fuse structure; the combination with a cylindrical tabular casing of insulating material, having internal screw threads at its opposite ends; of *metall c screw nipples threaded in said casing at its means fastening said nipples in said casing including respective screws extending ra l .iy through said casing and nipples; substantially semicylindrical metallic terminal members held in said nipples by said screws and having their inner faces extending in planes which are oblique to the axis of said casing, affording respective wedge abutnients; wedges respectively axi ally movable in said casing in opposition to said wedge abutments, having their inner 'aces' respectively inclined parallel with the inclined faces. of said abutments; said wedges having means to facilitate their withdrawal including grooves in the respective wedges extending obliquely with respect to the axis of said casing in the perimeters of said wedges; whereby said wedges are adapted to clamp a fuse, strip between them and-their respec ive abutments; screw caps respectively fitted to the outer ends of said nipples; cap washers, fitted in said caps in opposition to the outer ends of said wedges, and having respective o enings for electrical conductors; electrical conducting elements, respectively in integral relation with said wedge abutments and adapted to extend through the openings in said cap washers; said conducting elements being formed as plane blades which are'held in alinement with each other by said abutments; and a fuse strip extending in said casing, but clamped opposite ends;

oy said wedges, having its opposite ends extending through said cap washers.

2. in an electrical fuse structure; the combination with a tubular casing of insulating material, having internal screw threads at its opposite ends; of metallic screw nipples threaded in said casing at its opposite ends; means fastenin said nipples in said casing, including respective screws extending radially through said casing and nipples; sul stantially semicylindrical metallicterminal members heldin said nipples by said screws and having their inner faces extending in planes which are oblique to theaxis of said casing, affording respective wedge abutments; wedges respectively axially movable in said casing in opposition to said wedge abutments, having their inner faces respectively inclined parallel with the inclined faces of said abutments; whereby sail wedges are adapted to clamp a fuse strip between them and their respective abutments; screw caps respectively fitted to the outer ends ofsaid nipples; and cap washers, fitted in said caps in opposition to the outer ends of said wedges, and having respective openings for electrical conductors. i

In an electrical fuse structure; the combination with a tubular casing of insulating material; of metallic screw nipples in said casing at its opposite ends; means fastening said nipples in said casing, including respective screws extending through said casing Lil and nipples; substantially semicylindrical metallic terminal members held in said nipples by said screws and having their inner faces extending in planes which are oblique to the axis of said casing, affording respec tive wedge abutments; wedges respectively axially movable in said casing in opposition to said wedge abut-ments, having their inner faces respectively inclined parallel with the inclined faces of said abutments; whereby said wedges are adapted to clamp a fuse strip between them and their respective abutments; screw caps respectively fitted to the outer ends of said nipples; and cap washers, fitted in said caps 1n opposition to the outer ends of said wedges, and having respective openings for electrical conductors.

In an electrical fuse structure; the combination with a tul nlar casing insulating material; of metallic screw nipples in said casing at its opposite ends; metallic terminal members held in said nipples and having their inner faces extending in planes which are oblique to the axis of said casing, affording respective wedge abutments; wedges respectively axially movable in said casing in opposition to said wedge abutments, having their inner faces respectively inclined parallel with the inclined faces of said abutments; whereby said wedges are adapted to clamp a fuse strip between them and their respective abutments; and screw caps respectively fitted to the enter ends of said nipples.

5. In an electrical fuse structure; the combination with a tubular casing of insulating material; of metallic terminal members held in said casing having their inner faces extending in planes which are oblique to the axis of said casing, affording respective wedge abutments; wedges respectively axially movable in said casing in opposition to said wed e abutments, having their inner faces respectively inclined parallel with the inclined faces of said abutments; said wedges having means to facilitate their withdrawal including external grooves in the respective wedges; whereby said wedges are adapted to detachably clamp a fuse strip between them and their respective abutments; caps removably fitted at the opposite ends of said casing; and a fuse strip extending in said casing, clamped by said wedges, having one end extending through one of said caps.

(3. In an electrical fuse structure; the combination with a tubular casing of insulating material; of metallic terminal members held in said casing having their inner faces extendin in plane-s which are oblique to the axis of said casing, affording respective wedge abutments; wedges respectively axially movable in said casing in opposition to said wedge abut-ments, having their inner faces respectively inclined parallel with the inclined faces of said abutments; whereby said wedges are adapted to detachably clamp a fuse strip between them and their respective abutments; caps removably fitted at the opposite ends of said casing; and a fuse strip extending in said casing, clamped by said wedges, having one end extending through one of said caps.

7. In an electrical fuse structure; the combination with a tubular casing of insulating material; of metallic terminal members held in said casing, having their inner faces extending in planes which are oblique to the axis of said casing, affording respective wedge abutments; wedges respectively axially movable in said casing in opposition to said wedge abutments, having their inner faces respectively inclined parallel with the inclined faces, of said abutments; whereby said wedges are adapted to detachably clamp a fuse strip between them and their respective abutments; each end of said casing having a screw thread concentric with the casing axis, and means arranged to engage said terminal members; and screw caps carried by said casing, having means nor mally engaging said terminal members and preventing retraction of said wedges from clamped position; whereby it is necessary to rotate the respective caps before the respective wedges can be removed to release the fuse strip clamped thereby.

8. In an electrical fuse structure; the combination with a tubular casing; of a metallic terminal member fixed in said casing having aninner plane face extending in acute angular relation to the longitudinal axis of said casing, affording a wedge abutment; a wedge axially movable in said casing in opposition to said wedge abutment; whereby said wedge is adapted to detachably clamp a fuse strip against said abutment; caps on said casing normally preventing retraction of said wedges from clamping position; and means on said casing, engaging said caps; whereby it is necessary to turn said caps upon said casing, in coaxial relation therewith, to release the fuse strip clamped by said wedges.

9. In an electrical fuse structure; the combination with a tubular casing having a wedge abutment with a plane face inclined in acute angular relation to the axis of said tube, and a contact blade member, having opposite parallel plane faces in integral relation with said abutment; of a wedge adjustable axially in cooperative relation with said abutment, arranged to clamp a fuse strip in electrical connection with said blade.

In testimony whereof, I have hereunto signed my name at Philadelphia, Pennsylvania, this eighth day of September, 191.9.

HONARD DAVIES. 

